Connector

ABSTRACT

According to an aspect of the invention there is provided a connector for connecting inner and outer layers of an apparatus, the connector comprising: a first attachment part for attaching to one of the inner or outer layers; a second attachment part for attaching to the other of the inner or outer layers; wherein: the first and second attachment parts are connected in such a way as to allow the first attachment part and second attachment part to move relative to each other when the inner and outer layers move relative to each other, and the first attachment part comprises: a first flange portion adjacent a gap, said gap for accommodating a portion of said one of the inner or outer layers, said flange portion retaining said inner or outer layers within said gap, and wherein the first flange portion is substantially dome-shaped.

The present invention relates to connectors between inner and outer parts of an apparatus. In particular the present invention relates to an apparatus, such as a helmet, that may include a sliding interface between two components.

Helmets are known for use in various activities. These activities include combat and industrial purposes, such as protective helmets for soldiers and hard-hats or helmets used by builders, mine-workers, or operators of industrial machinery for example. Helmets are also common in sporting activities. For example, protective helmets may be used in ice hockey, cycling, motorcycling, motor-car racing, skiing, snow-boarding, skating, skateboarding, equestrian activities, American football, baseball, rugby, soccer, cricket, lacrosse, climbing, golf, airsoft, roller derby and paintballing.

Helmets can be of fixed size or adjustable, to fit different sizes and shapes of head. In some types of helmet, e.g. commonly in ice-hockey helmets, the adjustability can be provided by moving parts of the helmet to change the outer and inner dimensions of the helmet. This can be achieved by having a helmet with two or more parts which can move with respect to each other. In other cases, e.g. commonly in cycling helmets, the helmet is provided with an attachment device for fixing the helmet to the user's head, and it is the attachment device that can vary in dimension to fit the user's head whilst the main body or shell of the helmet remains the same size. In some cases, comfort padding within the helmet can act as the attachment device. The attachment device can also be provided in the form of a plurality of physically separate parts, for example a plurality of comfort pads which are not interconnected with each other. Such attachment devices for seating the helmet on a user's head may be used together with additional strapping (such as a chin strap) to further secure the helmet in place. Combinations of these adjustment mechanisms are also possible.

Helmets are often made of an outer shell, that is usually hard and made of a plastic or a composite material, and an energy absorbing layer called a liner. In other arrangements, such as a rugby scrum cap, a helmet may have no hard outer shell, and the helmet as a whole may be flexible. In any case, nowadays, a protective helmet has to be designed so as to satisfy certain legal requirements which relate to inter alia the maximum acceleration that may occur in the centre of gravity of the brain at a specified load. Typically, tests are performed, in which what is known as a dummy skull equipped with a helmet is subjected to a radial blow towards the head. This has resulted in modern helmets having good energy-absorption capacity in the case of blows radially against the skull. Progress has also been made (e.g. WO 2001/045526 and WO 2011/139224, which are both incorporated herein by reference, in their entireties) in developing helmets to lessen the energy transmitted from oblique blows (i.e. which combine both tangential and radial components), by absorbing or dissipating rotation energy and/or redirecting it into translational energy rather than rotational energy.

Such oblique impacts (in the absence of protection) result in both translational acceleration and angular acceleration of the brain. Angular acceleration causes the brain to rotate within the skull creating injuries on bodily elements connecting the brain to the skull and also to the brain itself.

Examples of rotational injuries include Mild Traumatic Brain Injuries (MTBI) such as concussion, and Severe Traumatic Brain Injuries (STBI) such as subdural haematomas (SDH), bleeding as a consequence of blood vessels rapturing, and diffuse axonal injuries (DAI), which can be summarized as nerve fibres being over stretched as a consequence of high shear deformations in the brain tissue.

Depending on the characteristics of the rotational force, such as the duration, amplitude and rate of increase, either concussion, SDH, DAI or a combination of these injuries can be suffered. Generally speaking, SDH occur in the case of accelerations of short duration and great amplitude, while DAI occur in the case of longer and more widespread acceleration loads.

In helmets such as those disclosed in WO 2001/045526 and WO 2011/139224 that may reduce the rotational energy transmitted to the brain caused by oblique impacts, two parts of the helmet may be configured to slide relative to each other following an oblique impact. Connectors may be provided that, whilst connecting the parts of a helmet together, permit movement of the parts relative to each other under an impact.

In order to provide such a helmet, it may be desirable to provide two components that can slide relative to each other, providing a sliding interface. It may also be desirable to be able to provide such a sliding interface without substantially increasing the manufacturing costs and/or effort.

According to a first aspect of the invention there is provided a connector for connecting inner and outer layers of an apparatus, the connector comprising: a first attachment part for attaching to one of the inner or outer layers; a second attachment part for attaching to the other of the inner or outer layers; wherein: the first and second attachment parts are connected in such a way as to allow the first attachment part and second attachment part to move relative to each other when the inner and outer layers move relative to each other, and the first attachment part comprises: a first flange portion adjacent a gap, said gap for accommodating a portion of said one of the inner or outer layers, said flange portion retaining said inner or outer layers within said gap, and wherein the first flange portion is substantially dome-shaped.

According to a second aspect of the invention there is provided a connector for connecting inner and outer layers of an apparatus, the connector comprising: a first attachment part for attaching to one of the inner or outer layers; a second attachment part for attaching to the other of the inner or outer layers; wherein: the first and second attachment parts are connected in such a way as to allow the first attachment part and second attachment part to move relative to each other when the inner and outer layers move relative to each other, and the first attachment part comprises: a first flange portion, adjacent a gap, said gap for accommodating a portion of said one of the inner or outer layer, said first flange portion retaining said inner or outer layers within said gap; separate first and second sections, the first section configured to connect directly to said one of the inner or outer layers, the second section configured to connect the rest of the connector to the first section, wherein: the first section of the first attachment part comprises: the first flanged portion located at a perimeter portion of the first section; a recessed portion, located at a central region of the first section, within the perimeter portion; a through hole through the recessed portion; and the second section of the first attachment part comprises: a further flanged portion configured to be located within the recessed portion of the first section, and a neck portion configured to pass through the through hole of the first section, the neck portion being connected to the rest of the connector.

Optionally, the first flanged portion of the first section and the flanged portion of the second section, when located therein, together form a substantially flat contiguous surface.

According to a third aspect of the invention there is provided a connector for connecting inner and outer layers of an apparatus, the connector comprising: a first attachment part for attaching to one of the inner or outer layers; a second attachment part for attaching to the other of the inner or outer layers; wherein: the first and second attachment parts are connected in such a way as to allow the first attachment part and second attachment part to move relative to each other when the inner and outer layers move relative to each other, and the second attachment part comprises: a first portion having a through hole therein; and a second portion passing through the through hole and configured to attach to said other of the inner or outer layers; wherein; the first portion of the second attachment part is configured such that the first portion can be threaded through a hole in said one of the inner or outer layers and the first attachment part is configured such that the first attachment part cannot be threaded through said hole.

Optionally, the second portion is removable from the through hole in the first portion of the second attachment part, and configured such that the second portion cannot be threaded through said hole, when located within the through hole in the first portion of the second attachment part.

Optionally, the second portion is a fastening means and comprises a snap pin.

Optionally, the first portion comprises an elongate tail protruding therefrom.

According to a fourth aspect of the invention, there is provided a connector for connecting inner and outer layers of an apparatus, the connector comprising: a first attachment part for attaching to one of the inner or outer layers; a second attachment part for attaching to the other of the inner or outer layers; and a resilient member connecting the first and second attachment parts; wherein: the resilient member is configured to be arranged between the inner and outer layers and to extend in a direction substantially parallel to a plane of the inner and outer layers, when the connector is attached to the inner and outer layers; and the resilient member is biased, when in a neutral state, in a direction perpendicular to a plane of the inner and outer layers, when the connector is attached to the inner and outer layers, such that when the first attachment part is attached to said one of the inner or outer layers, the second attachment part is pressed against said one of the inner or outer layers.

Optionally, the first attachment part comprises: first flange portion is adjacent a gap, said gap for accommodating a portion of said one of the inner or outer layers, said first flange portion retaining said inner or outer layers within said gap, and wherein the first flange portion is substantially dome-shaped.

Optionally, the first attachment part comprises: separate first and second sections, the first section configured to connect directly to said one of the inner or outer layers, the second section configured to connect the rest of the connector to the first section, wherein: the first section of the first attachment part comprises: first flange portions, located at a perimeter portion of the first section, separated by a gap, said gap for accommodating a portion of said one of the inner or outer layer, said flange portion retaining said inner or outer layers within said gap; a recessed portion, located at a central region of the first section, within the perimeter portion; a through hole through the recessed portion; and the second section of the first attachment part comprises: a flanged portion configured to be located within the recessed portion of the first section, and a neck portion configured to pass through the through hole of the first section, the neck portion being connected to the rest of the connector.

Optionally, the second attachment part comprises: an first portion having a through hole therein; and a second portion passing through the through hole and configured to attach to said other of the inner or outer layers; wherein; the elongate portion of the second attachment part is configured such that the elongate portion can be threaded through a hole in said one of the inner or outer layers and the first attachment part is configured such that the first attachment part cannot be threaded through said hole.

According to a fifth aspect of the invention, there is provided an apparatus comprising: inner and outer layers configured to move relative to each other; and at least one connector according to any of the preceding aspects connecting the inner and outer layers.

Optionally, the inner and outer layers are configured to move relative to each other at a sliding interface.

Optionally, the apparatus is an item of protective headgear.

Optionally, the first attachment part is attached to the inner layer.

Optionally, the inner layer is an interface layer configured to interface with the head of a wearer.

According to a sixth aspect of the invention there is provided a method of assembling an apparatus according to the fifth aspect of the invention, the method comprising: threading the second attachment part through a hole in said one of the inner or outer layers until the first attachment part is adjacent the hole; attaching the first attachment part to said one of the inner or outer layers, at the hole, via the first flange portion; and attaching the second attachment part to the other of the inner or outer layer.

The invention is described in detail below, with reference to the accompanying figures, in which:

FIG. 1 depicts a cross-section through a helmet for providing protection against oblique impacts;

FIG. 2 is a diagram showing the functioning principle of the helmet of FIG. 1 ;

FIGS. 3A, 3B & 3C show variations of the structure of the helmet of FIG. 1 ;

FIGS. 4 and 5 schematically depict another arrangement of a helmet;

FIGS. 6 to 9 schematically depict further arrangements of helmets;

FIG. 10 schematically depicts another arrangement of a helmet;

FIG. 11 schematically depicts another arrangement of a helmet;

FIG. 12 schematically depicts another arrangement of a helmet;

FIG. 13 shows a first view of a first example connector;

FIG. 14 shows a second view of the first example connector connected to an apparatus;

FIG. 15 shows a third view of the first example connector being threaded through a hole in a part of an apparatus;

FIG. 16 shows a first view of a second example connector;

FIG. 17 shows a first part of the second example connector;

FIG. 18 shows a second part of the second example connector;

FIG. 19 shows a second view of the second example connector connected to an apparatus;

FIG. 20 shows a third view of a second example connector connected to an apparatus.

The proportions of the thicknesses of the various layers in the helmets depicted in the figures have been exaggerated in the drawings for the sake of clarity and can of course be adapted according to need and requirements.

FIG. 1 depicts a first helmet 1 of the sort discussed in WO 01/45526, intended for providing protection against oblique impacts. This type of helmet could be any of the types of helmet discussed above.

Protective helmet 1 is constructed with an outer shell 2 and, arranged inside the outer shell 2, an inner shell 3 that is intended for contact with the head of the wearer.

Arranged between the outer shell 2 and the inner shell 3 is a sliding layer 4 (also called a sliding facilitator or low friction layer), which may enable displacement between the outer shell 2 and the inner shell 3. In particular, as discussed below, a sliding layer 4 or sliding facilitator may be configured such that sliding may occur between two parts during an impact. For example, it may be configured to enable sliding under forces associated with an impact on the helmet 1 that is expected to be survivable for the wearer of the helmet 1. In some arrangements, it may be desirable to configure the sliding layer 4 such that the coefficient of friction is between 0.001 and 0.3 and/or below 0.15.

Arranged in the edge portion of the helmet 1, in the FIG. 1 depiction, may be one or more connecting members 5 which interconnect the outer shell 2 and the inner shell 3. In some arrangements, the connectors may counteract mutual displacement between the outer shell 2 and the inner shell 3 by absorbing energy. However, this is not essential. Further, even where this feature is present, the amount of energy absorbed is usually minimal in comparison to the energy absorbed by the inner shell 3 during an impact. In other arrangements, connecting members 5 may not be present at all.

Further, the location of these connecting members 5 can be varied (for example, being positioned away from the edge portion, and connecting the outer shell 2 and the inner shell 3 through the sliding layer 4).

The outer shell 2 is preferably relatively thin and strong so as to withstand impact of various types. The outer shell 2 could be made of a polymer material such as polycarbonate (PC), polyvinylchloride (PVC) or acrylonitrile butadiene styrene (ABS) for example. Advantageously, the polymer material can be fibre-reinforced, using materials such as glass-fibre, Aramid, Twaron, carbon-fibre or Kevlar.

The inner shell 3 is considerably thicker and acts as an energy absorbing layer. As such, it is capable of damping or absorbing impacts against the head. It can advantageously be made of foam material like expanded polystyrene (EPS), expanded polypropylene (EPP), expanded polyurethane (EPU), vinyl nitrile foam; or other materials forming a honeycomb-like structure, for example; or strain rate sensitive foams such as marketed under the brand-names Poron™ and D3O™. The construction can be varied in different ways, which emerge below, with, for example, a number of layers of different materials.

Inner shell 3 is designed for absorbing the energy of an impact. Other elements of the helmet 1 will absorb that energy to a limited extent (e.g. the hard outer shell 2 or so-called ‘comfort padding’ provided within the inner shell 3), but that is not their primary purpose and their contribution to the energy absorption is minimal compared to the energy absorption of the inner shell 3. Indeed, although some other elements such as comfort padding may be made of ‘compressible’ materials, and as such considered as ‘energy absorbing’ in other contexts, it is well recognised in the field of helmets that compressible materials are not necessarily ‘energy absorbing’ in the sense of absorbing a meaningful amount of energy during an impact, for the purposes of reducing the harm to the wearer of the helmet.

A number of different materials and embodiments can be used as the sliding layer 4 or sliding facilitator, for example oil, Teflon, microspheres, air, rubber, polycarbonate (PC), a fabric material such as felt, etc. Such a layer may have a thickness of roughly 0.1-5 mm, but other thicknesses can also be used, depending on the material selected and the performance desired. The number of sliding layers and their positioning can also be varied, and an example of this is discussed below (with reference to FIG. 3 b ).

As connecting members 5, use can be made of, for example, deformable strips of plastic or metal which are anchored in the outer shell and the inner shell in a suitable manner.

FIG. 2 shows the functioning principle of protective helmet 1, in which the helmet 1 and a skull 10 of a wearer are assumed to be semi-cylindrical, with the skull 10 being mounted on a longitudinal axis 11. Torsional force and torque are transmitted to the skull 10 when the helmet 1 is subjected to an oblique impact K. The impact force K gives rise to both a tangential force K_(T) and a radial force K_(R) against the protective helmet 1. In this particular context, only the helmet-rotating tangential force K_(T) and its effect are of interest.

As can be seen, the force K gives rise to a displacement 12 of the outer shell 2 relative to the inner shell 3, the connecting members 5 being deformed. Significant reductions in the torsional force transmitted to the skull 10 can be obtained with such an arrangement. A typical reduction may be roughly 25% but reductions as high as 90% may be possible in some instances. This is a result of the sliding motion between the inner shell 3 and the outer shell 2 reducing the amount of energy which is transferred into radial acceleration.

Sliding motion can also occur in the circumferential direction of the protective helmet 1, although this is not depicted. This can be as a consequence of circumferential angular rotation between the outer shell 2 and the inner shell 3 (i.e. during an impact the outer shell 2 can be rotated by a circumferential angle relative to the inner shell 3).

Other arrangements of the protective helmet 1 are also possible. A few possible variants are shown in FIG. 3 . In FIG. 3 a , the inner shell 3 is constructed from a relatively thin outer layer 3″ and a relatively thick inner layer 3′. The outer layer 3″ is preferably harder than the inner layer 3′, to help facilitate the sliding with respect to outer shell 2. In FIG. 3 b , the inner shell 3 is constructed in the same manner as in FIG. 3 a . In this case, however, there are two sliding layers 4, between which there is an intermediate shell 6. The two sliding layers 4 can, if so desired, be embodied differently and made of different materials. One possibility, for example, is to have lower friction in the outer sliding layer than in the inner. In FIG. 3 c , the outer shell 2 is embodied differently from previously. In this case, a harder outer layer 2″ covers a softer inner layer 2′. The inner layer 2′ may, for example, be the same material as the inner shell 3.

FIG. 4 depicts a second helmet 1 of the sort discussed in WO 2011/139224, which is also intended for providing protection against oblique impacts. This type of helmet could also be any of the types of helmet discussed above.

In FIG. 4 , helmet 1 comprises an energy absorbing layer 3, similar to the inner shell 3 of the helmet of FIG. 1 . The outer surface of the energy absorbing layer 3 may be provided from the same material as the energy absorbing layer 3 (i.e. there may be no additional outer shell), or the outer surface could be a rigid shell 2 (see FIG. 5 ) equivalent to the outer shell 2 of the helmet shown in FIG. 1 . In that case, the rigid shell 2 may be made from a different material than the energy absorbing layer 3. The helmet 1 of FIG. 4 has a plurality of vents 7, which are optional, extending through both the energy absorbing layer 3 and the outer shell 2, thereby allowing airflow through the helmet 1.

An interface layer 13 (also called an attachment device) is provided, to interface with (and/or attach helmet 1 to) a wearer's head. As previously discussed, this may be desirable when energy absorbing layer 3 and rigid shell 2 cannot be adjusted in size, as it allows for the different size heads to be accommodated by adjusting the size of the attachment device 13. The attachment device 13 could be made of an elastic or semi-elastic polymer material, such as PC, ABS, PVC or PTFE, or a natural fibre material such as cotton cloth. For example, a cap of textile or a net could form the attachment device 13.

Although the attachment device 13 is shown as comprising a headband portion with further strap portions extending from the front, back, left and right sides, the particular configuration of the attachment device 13 can vary according to the configuration of the helmet. In some cases the attachment device may be more like a continuous (shaped) sheet, perhaps with holes or gaps, e.g. corresponding to the positions of vents 7, to allow air-flow through the helmet.

FIG. 4 also depicts an optional adjustment device 6 for adjusting the diameter of the head band of the attachment device 13 for the particular wearer. In other arrangements, the head band could be an elastic head band in which case the adjustment device 6 could be excluded.

A sliding facilitator 4 is provided radially inwards of the energy absorbing layer 3. The sliding facilitator 4 is adapted to slide against the energy absorbing layer or against the attachment device 13 that is provided for attaching the helmet to a wearer's head.

The sliding facilitator 4 is provided to assist sliding of the energy absorbing layer 3 in relation to an attachment device 13, in the same manner as discussed above. The sliding facilitator 4 may be a material having a low coefficient of friction, or may be coated with such a material.

As such, in the FIG. 4 helmet, the sliding facilitator 8 may be provided on or integrated with the innermost side of the energy absorbing layer 3, facing the attachment device 13.

However, it is equally conceivable that the sliding facilitator 4 may be provided on or integrated with the outer surface of the attachment device 13, for the same purpose of providing slidability between the energy absorbing layer 3 and the attachment device 13. That is, in particular arrangements, the attachment device 13 itself can be adapted to act as a sliding facilitator 4 and may comprise a low friction material.

In other words, the sliding facilitator 4 is provided radially inwards of the energy absorbing layer 3. The sliding facilitator can also be provided radially outwards of the attachment device 13.

When the attachment device 13 is formed as a cap or net (as discussed above), sliding facilitators 4 may be provided as patches of low friction material.

The low friction material may be a waxy polymer, such as PTFE, ABS, PVC, PC, Nylon, PFA, EEP, PE and UHMWPE, or a powder material which could be infused with a lubricant. The low friction material could be a fabric material. As discussed, this low friction material could be applied to either one, or both of the sliding facilitator and the energy absorbing layer.

The attachment device 13 can be fixed to the energy absorbing layer 3 and/or the outer shell 2 by means of fixing members 5, such as the four fixing members 5 a, 5 b, 5 c and 5 d in FIG. 4 . These may be adapted to absorb energy by deforming in an elastic, semi-elastic or plastic way. However, this is not essential. Further, even where this feature is present, the amount of energy absorbed is usually minimal in comparison to the energy absorbed by the energy absorbing layer 3 during an impact.

According to the arrangement shown in FIG. 4 the four fixing members 5 a, 5 b, 5 c and 5 d are suspension members 5 a, 5 b, 5 c, 5 d, having first and second portions 8, 9, wherein the first portions 8 of the suspension members 5 a, 5 b, 5 c, 5 d are adapted to be fixed to the attachment device 13, and the second portions 9 of the suspension members 5 a, 5 b, 5 c, 5 d are adapted to be fixed to the energy absorbing layer 3.

FIG. 5 shows an arrangement of a helmet similar to the helmet in FIG. 4 , when placed on a wearer's head. The helmet 1 of FIG. 5 comprises a hard outer shell 2 made from a different material than the energy absorbing layer 3. In contrast to FIG. 4 , in FIG. 5 the attachment device 13 is fixed to the energy absorbing layer 3 by means of two fixing members 5 a, 5 b, which are adapted to absorb energy and forces elastically, semi-elastically or plastically.

A frontal oblique impact I creating a rotational force to the helmet is shown in FIG. 5 . The oblique impact I causes the energy absorbing layer 3 to slide in relation to the attachment device 13. The attachment device 13 is fixed to the energy absorbing layer 3 by means of the fixing members 5 a, 5 b. Although only two such fixing members are shown, for the sake of clarity, in practice many such fixing members may be present. The fixing members 5 can absorb the rotational forces by deforming elastically or semi-elastically. In other arrangements, the deformation may be plastic, even resulting in the severing of one or more of the fixing members 5. In the case of plastic deformation, at least the fixing members 5 will need to be replaced after an impact. In some case a combination of plastic and elastic deformation in the fixing members 5 may occur, i.e. some fixing members 5 rupture, absorbing energy plastically, whilst other fixing members deform and absorb forces elastically.

In general, in the helmets of FIG. 4 and FIG. 5 , during an impact the energy absorbing layer 3 acts as an impact absorber by compressing, in the same way as the inner shell of the FIG. 1 helmet. If an outer shell 2 is used, it will help spread out the impact energy over the energy absorbing layer 3. The sliding facilitator 4 will also allow sliding between the attachment device and the energy absorbing layer. This allows for a controlled way to dissipate energy that would otherwise be transmitted as rotational energy to the brain. The energy can be dissipated by friction heat, energy absorbing layer deformation or deformation or displacement of the fixing members. The reduced energy transmission results in reduced rotational acceleration affecting the brain, thus reducing the rotation of the brain within the skull. The risk of rotational injuries including MTBI and STBI such as subdural haematomas, SDH, blood vessel rapturing, concussions and DAI is thereby reduced.

Connectors that may be used within a helmet are described below. It should be appreciated that these connectors may be used in a variety of contexts and are not to be limited to use within helmets. For example, they may be used in other devices that provide impact protection, such as body armour or padding for sports equipment. In the context of helmets, the connectors may, in particular, be used in place of the previously known connecting members and/or fixing members of the arrangements discussed above.

In an arrangement, the connector may be used with a helmet 1 of the type shown in FIG. 6 . The helmet shown in FIG. 6 has a similar configuration to that discussed above in respect of FIGS. 4 and 5 . In particular, the helmet has a relatively hard outer shell 2 and an energy absorbing layer 3. A head attachment device is provided in the form of a helmet liner 15. The liner 15 may include comfort padding as discussed above. In general, the liner 15 and/or any comfort padding may not absorb a significant proportion of the energy of an impact in comparison with the energy absorbed by the energy absorbing layer 3.

The liner 15 may be removable. This may enable the liner to be cleaned and/or may enable the provision of liners that are modified to fit a specific wearer.

Between the liner 15 and the energy absorbing layer 3, there is provided an inner shell 14 formed from a relatively hard material, namely a material that is harder than the energy absorbing layer 3. The inner shell 14 may be moulded to the energy absorbing layer 3 and may be made from any of the materials discussed above in connection with the formation of the outer shell 2. In alternative arrangements, the inner shell 14 may be formed from a fabric material, optionally coated with a low friction material.

In the arrangement of FIG. 6 , a low friction interface is provided between the inner shell 14 and the liner 15. This may be implemented by the appropriate selection of at least one of the material used to form the outer surface of the liner 15 or the material used to form the inner shell 14. Alternatively or additionally, a low friction coating may be applied to at least one of the opposing surfaces of the inner shell 14 and the liner 15. Alternatively or additionally, a lubricant may be applied to at least one of the opposing surfaces of the inner shell 14 and the liner 15.

As shown, the liner 15 may be connected to the remainder of the helmet 1 by way of one or more connectors 20, discussed in further detail below. Selection of the location of the connectors 20 and the number of connectors 20 to use may depend upon the configuration of the remainder of the helmet.

In an arrangement such as shown in FIG. 6 , at least one connector 20 may be connected to the inner shell 14. Alternatively or additionally, one or more of the connectors 20 may be connected to another part of the remainder of the helmet 1, such as the energy absorbing layer 3 and/or the outer shell 2. The connectors 20 may also be connected to two or more parts of the remainder of the helmet 1.

FIG. 7 depicts a further alternative arrangement of a helmet 1. As shown, the helmet 1 of this arrangement includes a plurality of independent sections of comfort padding 16. Each section of comfort padding 16 may be connected to the remainder of the helmet by one or more connectors 20.

The sections of comfort padding 16 may have a sliding interface provided between the sections of comfort padding 16 and the remainder of the helmet 1. In such an arrangement, the sections of comfort padding 16 may provide a similar function to that of the liner 15 of the arrangement shown in FIG. 6 . The options discussed above for provision of a sliding interface between a liner and a helmet also apply to the sliding interface between the sections of comfort padding and the helmet.

It should also be appreciated that the arrangement of FIG. 7 , namely the provision of a plurality of independently mounted sections of comfort padding 16 provided with a sliding interface between the sections of comfort padding 16 and the remainder of the helmet, may be combined with any form of helmet, including those such as depicted in FIGS. 1 to 5 that also have a sliding interface provided between two other parts of the helmet.

FIGS. 8 and 9 show equivalent arrangements to those of FIGS. 6 and 7 , except that the inner shell 14 is applied to the liner 15 (in FIG. 8 ) or comfort padding 16 (in FIG. 9 ). In the case of FIG. 9 , the inner shell 14 may only be a partial shell or a plurality of sections of shell, as compared to the substantially full shell arrangements of FIGS. 6 to 8 . Indeed, in both FIGS. 8 and 9 the inner shell 14 may also be characterised as a relatively hard coating on the liner 15 or comfort padding 16. As for FIGS. 6 and 7 , the inner shell 14 is formed from a relatively hard material, namely a material that is harder than the energy absorbing layer 3. For example, the material could be PTFE, ABS, PVC, PC, Nylon, PFA, EEP, PE and UHMWPE. The material may be bonded to the outer side of the liner 15 or comfort padding 16 to simplify the manufacturing process. Such bonding could be through any means, such as by adhesive or by high frequency welding or stitching. In alternative arrangements, the inner shell 14 may be formed from a fabric material, optionally coated with a low friction material.

In FIGS. 8 and 9 a low friction interface is provided between the inner shell 14 and the energy absorbing layer 3. This may be implemented by the appropriate selection of at least one of the material used to form the outer surface of the energy absorbing layer 3 or the material used to form the inner shell 14. Alternatively or additionally, a low friction coating may be applied to at least one of the opposing surfaces of the inner shell 14 and the energy absorbing layer 3. Alternatively or additionally, a lubricant may be applied to at least one of the opposing surfaces of the inner shell 14 and the energy absorbing layer 3.

In FIGS. 8 and 9 , at least one connector 20 may be connected to the inner shell 14. Alternatively or additionally, one or more of the connectors 20 may be connected to another part of the remainder of the liner 15 or comfort padding 16.

In another arrangement, the connector may be used with a helmet 1 of the type shown in FIG. 10 . The helmet shown in FIG. 10 has a similar configuration to that discussed above in respect of FIGS. 1, 2, 3A and 3B. In particular, the helmet has a relatively hard outer shell 2 and an energy absorbing layer 3 configured to slide relative to each other. At least one connector 20 may be connected to the outer shell 2 and the energy absorbing layer 3. Alternatively, the connector may be connected one or more intermediate sliding layers associated with one or both of the outer shell 2 and the energy absorbing layer 2, which provide low friction.

In yet another arrangement, the connector may be used with a helmet 1 of the type shown in FIG. 11 . The helmet shown in FIG. 11 has a similar configuration to that discussed above in respect of FIG. 3B. In particular, the helmet has a relatively hard outer shell 2 and an energy absorbing layer 3 which is divided into outer and inner parts 3A, 3B 3 configured to slide relative to each other. At least one connector 20 may be connected to the outer and inner parts 3A, 3B of the energy absorbing layer 3. Alternatively, the connector may be connected one or more intermediate sliding layers associated with one or both of the outer and inner parts 3A, 3B of the energy absorbing layer 3, which provide low friction.

FIG. 12 depicts yet another alternative arrangement of a helmet 1. In this arrangement, one or more outer plates 17 may be mounted to a helmet 1 having at least an energy absorbing layer 3 and a relatively hard layer 2 formed outward of the energy absorbing layer 2. It should be understood that such an arrangement of outer plates 17 may be added to any helmet according to any of the arrangements discussed above, namely having a sliding interface between at least two of the layers of the helmet 1.

The outer plates 17 may be mounted to the relatively hard layer 2 in a manner that provides a low friction interface between the outer surface of the relatively hard layer 2 and that least a part of a surface of the outer plate 17 that is in contact with the outer surface of the relatively hard layer 2, at least under an impact to the outer plate 17. In some arrangements, an intermediate low friction layer may be provided between the hard layer 2 and the plates 17

In addition, the manner of mounting the outer plates 17 may be such that, under an impact to an outer plate 17, the outer plate 17 can slide across the relatively hard layer 2 (or intermediate low friction layer). Each outer plate 17 may be connected to the remainder of the helmet 1 by one or more connectors 20.

In such an arrangement, in the event of an impact on the helmet 1, it can be expected that the impact would be incident on one or a limited number of the outer plates 17. Therefore, by configuring the helmet such that the one or more outer plates 17 can move relative to the relatively hard layer 2 and any outer plates 17 that have not been subject to an impact, the surface receiving the impact, namely one or a limited number of outer plates 17, can move relative to the remainder of the helmet 1. In the case of an oblique impact or a tangential impact, this may reduce the transfer of rotational forces to the remainder of the helmet. In turn, this may reduce the rotational acceleration imparted on the brain of a wearer of the helmet and/or reduce brain injuries.

FIGS. 13 to 15 show different views of a first example connector 20 in accordance with the disclosure. As explained above, the connector 20 is for connecting inner and outer layers of an apparatus, such as a helmet.

The connector 20 comprises a first attachment part 21 for attaching the connector 20 to one of the inner or outer layers and a second attachment part 22 for attaching the connector 20 to the other of the inner or outer layers. The first and second attachment parts 21, 22 are connected in such a way as to allow the first attachment part and second attachment part to move relative to each other when the inner and outer layers move relative to each other. In the present example, the first and second attachment parts 21, 22 are connected by a resilient member 23. Features of the first attachment part 21, second attachment part 22 and resilient member 23 will be described in further detail below.

FIGS. 13 and 14 show the first attachment part 21 in detail. As shown, the first attachment part 21 comprises a first flange portion 211. The first flange portion 211 is attached to the resilient member 23 by a neck portion 212. As shown best in FIG. 14 , the neck portion 212 bends at an angle of approximately 90 degrees such that a central axis through the first flange portion 211 is substantially perpendicular to a central axis through the resilient portion 23.

The neck portion 212 means that, although the attachment between the first attachment part 21 and the inner or outer layer of the apparatus is made in a direction substantially perpendicular to the inner or outer layer of the apparatus, the connector 20 itself extends substantially parallel to the inner or outer layer of the apparatus, as shown in FIG. 14 .

The first attachment part 21 further comprises second flange portions 213. As shown, these maybe arranged on the neck portion 212. The first and second flange portions 211, 213 may be arranged to oppose each other and be separated by a gap 214. As shown in FIG. 14 , the gap 214 maybe configured to accommodate a portion of one of the inner or outer layers to which the first attachment part 21 is connected and retain that part within the gap 214. In some examples, a portion of the resilient member 23 may function as a second flange portion. The example shown in FIG. 14 is such an example, although additional second flange portions 213 are also provided. The first and second flange portions 211, 213 are therefore able to fix the first attachment part 21 in position relative to the inner or outer layer of the apparatus.

As shown in FIGS. 13 to 15 , the first flange portion 211 may be substantially dome shaped. It should be noted that the dome shape could have a circular profile, as shown in the figures, but it is not limited so. The profile may alternatively be oval or elliptical, for example. The term dome shape may refer to a substantially smooth, curved, convex shape. The underside surface of a peripheral portion of the dome may face the second flange portions 213 across the gap 14.

As shown in FIG. 14 , when the first attachment part 21 is connected to one of the inner or outer layers of the helmet, such that the inner or outer layer is retained within the gap between the flange portions 211 and 213, the dome shape of the first flange portion 211 results in a relatively stream lined arrangement having a small profile. Preferably, the dome shaped first flange portion 211 is substantially flat. For example, the dome shaped first flange portion 211 may have a thickness of between 0.5 and 2 millimetres, e.g. around 1 millimetre. The smoothness of the dome shape, i.e. lack of sharp corners, reduces the point pressure that would be felt if the first flange portion 211 were to come into contact with the wearer of the apparatus. Further, the shape of the dome may prevent the hair of a wearer becoming trapped by the first attachment part 21.

The second attachment part 22 comprises a first portion 221 having a through hole 222 therein, as best shown in FIG. 15 . As shown in FIGS. 13 and 14 , a second portion 223, which may be a fastening means, passes through the through hole 222 and is configured to attach to one of the inner or outer layers of a helmet. Preferably, the second portion 223 is removable from the through hole 222 to be separated from the first portion 221. The first portion 221 may extend substantially in the same direction as the resilient member 23 connecting the first and second attachment parts 21, 22. The through hole 222 may be provided perpendicularly to the extension direction of the first portion 221. The though hole may also extend in a direction substantially parallel to the central axis through the first attachment part 21.

As shown in FIG. 14 , the fastening means 223 may comprise a snap-pin 224 configured to engage with a snap basket 31 in the inner or outer layer of the apparatus to which the second attachment part 22 is connected. As shown, the snap-pin 224 maybe connected to a flange portion 225 (e.g. a plate) larger than the through hole 222, in order to retain the snap-pin 224 within the through hole 222. The second portion 223 may be formed from a relatively hard material compared to the first portion 221. The orientation of the through hole 222 may mean that, although the attachment between the second attachment part 21 and the inner or outer layer of the apparatus is made in a direction substantially perpendicular to the inner or outer layer of the apparatus, the connector 20 itself extends substantially parallel to the inner or outer layer of the apparatus, as shown in FIG. 14 .

As shown in FIG. 15 , the first portion 221 of the second attachment part 22 is configured such that the first portion 221 can be threaded through a hole 41 in the inner or outer layer of the apparatus to which the first attachment part 21 is to be connected.

As shown in FIGS. 13 to 15 , the first portion 221 may have one or more substantially flat surfaces, arranged such that the through hole 222 is formed in said surfaces. Preferably, the thickness of the first portion 221 (in the direction of the through hole 222) is relatively small compared to the width and length of the first portion 221. Preferably, still the width of the first portion 221 should be no larger than the length of the of the first portion 221. For example, the first portion 221 may be elongate in shape, extending in a direction parallel to the resilient member 23. The first portion 221 may be substantially oblong in shape, as shown in the Figures. However, other shapes may be used, e.g. oval, or rectangular. Such shapes may allow the first portion to be threaded more easily through the hole 41.

In contrast, the first attachment part 21 is configured such that the first attachment part 21 cannot be threaded through said hole 41. The hole 41 is configured to surround the neck portion 212 of the first attachment part 21 such that an edge of the hole 41 is located between the first and second flange portions 211 and 213, within the gap 214. Accordingly, the width of the first flange portion 211 is larger than the width of the hole 41. The difference between the width of the first flange portion 211 and the width of the hole 41 is preferably large enough such that the first flange portion 211 cannot easily be deformed to fit through the hole 41.

Preferably, the second portion 223 of the second attachment part 22 is configured such that the second portion 223 cannot be threaded through the hole 41, when located within the through hole 222 in the first portion 221 of the second attachment part 22. With the above described arrangement, once the connector 20 is correctly attached, it is difficult to detach.

As shown, the cross-sectional shape of the first portion 221 may be substantially rectangular. A rectangular shape reduces the thickness of the first portion 221 while providing enough space for the through hole 222. However, any shape maybe used. As shown in FIG. 15 , the shape of the hole 41 may substantially correspond to a cross-sectional shape of the first portion 221. However, this is not necessarily required.

The resilient member 23 may be configured to deform elastically, semi-elastically, or plastically to allow the first attachment part 21 and second attachment part 22 to move relative to each other. Accordingly, the resilient member 23 may be formed from a resilient material, such as natural or synthetic rubber (e.g. silicone rubber), PP(polypropylene), PU(Polyurethane) or similar, TPE(Thermoplastic elastomer), or combinations and mixtures thereof. The resilient member 23 may be configured to bend in any direction. However, it may be permissible for the resilient member 23 to be configured to bend substantially only in a plane parallel to the inner and outer layers of the apparatus. The resilient member 23 may also be configured to stretch along its axis.

As shown in FIG. 13 , the resilient member 23 may be biased, when in a neutral state, in a direction perpendicular to a plane of the inner and outer layers, when the connector 20 is attached to the inner and outer layers. Accordingly, when a first attachment part 21 is attached to one of the inner or outer layers, the second attachment part 22 may be pressed against said inner or outer layer, as shown in FIG. 14 . Accordingly, the resilient member 23 is bent in a direction perpendicular to a central axis through the resilient member 23. This arrangement means that the connector 20 remains substantially parallel to the inner or outer layer to which the first attachment part 21 is connected, during installation, making it easier to connect the second attachment part 22 to the other of the inner or outer layers.

The resilient portion 23 is preferably an elongate member, as shown in FIGS. 13 to 15 . The cross-sectional shape of the resilient member 23 could be oval (as shown in the Figures), circular, or any other shape. The cross sectional shape of the resilient portion 23 should be such that it can be threaded through the hole 41. The dimensions of the resilient portion 23 should be such that it allows at least an amount of deformation required to allow the first and second attachment parts 21, 22 to move relative to each other as required. This may be to allow a displacement of between 5 mm and 30 mm, or preferably 10 mm to 15 mm, in any direction, for example.

As shown in the Figures, the first attachment part 21 may be formed from the same material as the resilient portion 23. As shown in the Figures, the first portion 221 of the second attachment part 22 may be formed from the same material as the resilient portion 23. The resilient member 23 may be formed as one with the first attachment part 21 and/or the first portion 221 of the second attachment part 22. Alternatively, these parts may be made from different materials attached or co-moulded together.

FIGS. 16 to 19 show a second example connector 20 in accordance with the disclosure. The second example connector 20 comprises a resilient portion 23 and second attachment part 22 that are substantially the same as those of the first example connector 20. However, as shown in FIG. 16 , the first portion 221 of the second attachment part 22 further comprises an elongate tail 226 protruding therefrom. As shown, the tail 226 extends substantially in the same direction as the first portion 221. The tail 226 is configured to assist with threading the first portion 221 through the hole 41 by provided a part that can be more easily grasped and pulled through the hole 41.

As shown in FIG. 16 , the first attachment part 22 is different from the first attachment part 22 of the first example connector 20. In the second example connector 20, the first attachment part 21 comprises separate first and second sections 215 and 216, respectively shown in FIGS. 17 and 18 . The first section 215 comprises a first flange portion 217 at perimeter portion of the first section 215. The first section 215 further comprises a recessed portion 218, located at a central portion of the first section 215, within the perimeter portion, and a through hole 219 through the recessed portion 218.

The second section 216 of the first attachment part 21 comprises a flanged portion 2110 configured to be located within the recessed portion 218 of the first section 215 and a neck portion 212 configured to pass through the through hole 219 of the first section 215. The neck portion 212 is connected to the rest of the connector 20. Preferably, the first flange portion 217 of the first section 215 and the flange portion 2110 of the second section 218, when located therein, together may form a substantially flat contiguous surface. In other words the top surfaces of the first flange portion 217 of the first section 215 and the flange portion 2110 of the second section 218 may be substantially level with each other. The flatness, i.e. lack of substantial undulations or corners, reduces the point pressure that would be felt if the surface of first attachment part 21 were to come into contact with the wearer of the apparatus.

The first and second sections 215, 216 of the first attachment part 21 may be configured so as to be assembled together by threading the rest of the connector 20 through the through hole 219 until the flange portion 2110 is located in the recessed portion 218. Accordingly the first portion 221 of the second attachment part 22 may be of a size and shape to pass through the through hole 219.

The first section 215 of the first attachment part 21 may comprise a second flange portion 2112, both the second flange portion 2112 and the first flange portion 217 adjacent a gap 214. The gap 214 may be for accommodating a portion of one of the inner or outer layers to which the first attachment part 21 is to be connected, and retain the inner or outer layer within the gap 214. Alternatively, second flange portions may be provided on the neck portion 212 or the resilient member 23 may function as a second flange portion.

The first section 215 of the first attachment part 21 may be formed from a relatively hard material (such as PP(polypropylene, PA(polyamide), POM(Polyoxymethylene), PC(polycarbonate), wood, or metal such as aluminium or steel). However, the neck portion 212 may be formed from a resilient material. For example, this material may be the same material as the material forming the resilient member 23. The resilient member 23 may be formed as one with the neck portion 212 of the first attachment part 21. Alternatively, these parts may be made from different materials attached or co-moulded together.

It should be understood that connectors 20 within the scope of the present disclosure, may comprise a first attachment part 21, second attachment part 22 and/or resilient portion different to those described above. For example, a connector 20 within the scope of the present disclosure may comprise only one, or only two parts selected from the first attachment part 21, second attachment part 22 and resilient portion 23 described above, with the remaining parts being different.

As described above, features of the inner and/or outer layers of the apparatus may be configured for attachment to the first and second attachments parts 21, 22 of the first and second example connectors 20. For example, one of the inner or outer layers may comprise a hole 41 for attachment of the first attachment part 21. One of the inner or outer layers may comprise a mechanism for attachment of the fastening means of the second attachment part 22 thereto, such as a snap basket 31.

In view of the above arrangements, it may be preferable, but not essential, that the hole 41 be formed in a relatively thin layer. This may make it easier to attach the first attachment part 21. In some examples, the hole 41 may be formed in a recessed portion of the layer. The recessed portion may be configured to accommodate the first attachment part. This arrangement may further help to reduce the point pressure that would be felt if the first flange portion 211 were to come into contact with the wearer of the apparatus or prevent the hair of a wearer becoming trapped by the first attachment part 21. Furthermore, the edges of the hole 41 may be rounded (e.g. rather than squared). The round edge may be formed by the shape of a punching tool used to form the hole 41. This feature may increase the lifespan of the apparatus by reducing wear between the hole 41 and the connector.

Similarly, it may be preferable, that the mechanism 31 for attachment of the fastening means be provided in a relatively thick layer. This may allow the mechanism 31 to be fixed more securely in the layer.

A preferred arrangement for an apparatus may be an outer layer that is an energy absorbing layer 3 and an inner layer that is an interface layer 13, such as the arrangement shown in FIG. 1 and described above. FIGS. 14, 19 and 20 show the example connectors 20 as part of connection arrangements, within an apparatus. FIG. 14 shows an outer layer of the apparatus, said outer layer being an energy absorbing layer 3. FIGS. 14, 19 and 20 show an inner layer of the apparatus, said inner layer being an interface layer 13.

A method of assembling an apparatus in accordance with the disclosure will now be described, with reference to FIGS. 14, 15, 19 and 20 , and an arrangement in which the first attachment part 21 is connected to an interface layer 13 and the second attachment part is connected to an energy absorbing layer 3. As partly shown in FIG. 15 , the method comprises threading the second attachment part 22 through the hole 41 in the interface layer 13 until the first attachment part 21 is adjacent the hole 41. As shown in FIG. 19 and close-up in FIG. 20 , the first attachment part 22 is then attached to the interface layer, at the hole 41, via the first and second flange portions 211, 213 and 217, 2112. This may be a snap-fit attachment. As shown in FIG. 14 , the second attachment part 22 is attached to the energy absorbing layer 3, e.g. via the fastening means 223 and corresponding mechanism 31.

The method may include a step of assembling the second attachment part 22 by locating the fastening means 223 in the through hole 222. This may be done after the step of the second attachment part 22 through the hole 41. In the case of the second example connector 20, the method may include a step of assembling the first attachment part 21 by locating the second portion 216 within the first portion 215. This may be done before the step of the second attachment part 22 through the hole 41. Alternatively, this may be done after or during the step of the second attachment part 22 through the hole 41. For example, the first portion 215 of the first attachment part 21 may be pre-attached to the interface layer, then the second attachment part may be threaded through the first portion 215 of the first attachment part 21 and the hole 41.

It should be appreciated that the connector 20 may be used for connecting any two parts of an apparatus together, e.g. any of the layers described above. Furthermore, where the connector 20 is described as having a first part connected to a first part of an apparatus, e.g. an interface layer, and a second part connected to a second part of an apparatus, e.g. an energy absorbing layer, it should be appreciated that, with suitable modifications, this may be reversed.

Variations of the above described embodiments are possible in light of the above teachings. It is to be understood that the invention may be practiced otherwise and specifically described herein without departing from the spirit and scope of the invention. 

1. A connector for connecting inner and outer layers of an apparatus, the connector comprising: a first attachment part for attaching to one of the inner or outer layers; a second attachment part for attaching to the other of the inner or outer layers; wherein: the first and second attachment parts are connected in such a way as to allow the first attachment part and second attachment part to move relative to each other when the inner and outer layers move relative to each other, and the first attachment part comprises: a first flange portion adjacent a gap, said gap for accommodating a portion of said one of the inner or outer layers, said flange portion retaining said inner or outer layers within said gap, and wherein the first flange portion is substantially dome-shaped.
 2. A connector for connecting inner and outer layers of an apparatus, the connector comprising: a first attachment part for attaching to one of the inner or outer layers; a second attachment part for attaching to the other of the inner or outer layers; wherein: the first and second attachment parts are connected in such a way as to allow the first attachment part and second attachment part to move relative to each other when the inner and outer layers move relative to each other, and the first attachment part comprises: a first flange portion, adjacent a gap, said gap for accommodating a portion of said one of the inner or outer layer, said first flange portion retaining said inner or outer layers within said gap; separate first and second sections, the first section configured to connect directly to said one of the inner or outer layers, the second section configured to connect the rest of the connector to the first section, wherein: the first section of the first attachment part comprises: the first flanged portion located at a perimeter portion of the first section; a recessed portion, located at a central region of the first section, within the perimeter portion; a through hole through the recessed portion; and the second section of the first attachment part comprises: a further flanged portion configured to be located within the recessed portion of the first section, and a neck portion configured to pass through the through hole of the first section, the neck portion being connected to the rest of the connector.
 3. The connector of claim 2, wherein the first flanged portion of the first section and the flanged portion of the second section, when located therein, together form a substantially flat contiguous surface.
 4. A connector for connecting inner and outer layers of an apparatus, the connector comprising: a first attachment part for attaching to one of the inner or outer layers; a second attachment part for attaching to the other of the inner or outer layers; wherein: the first and second attachment parts are connected in such a way as to allow the first attachment part and second attachment part to move relative to each other when the inner and outer layers move relative to each other, and the second attachment part comprises: a first portion having a through hole therein; and a second portion passing through the through hole and configured to attach to said other of the inner or outer layers; wherein; the first portion of the second attachment part is configured such that the first portion can be threaded through a hole in said one of the inner or outer layers and the first attachment part is configured such that the first attachment part cannot be threaded through said hole.
 5. The connector of claim 4, wherein the second portion is removable from the through hole in the first portion of the second attachment part, and configured such that the second portion cannot be threaded through said hole, when located within the through hole in the first portion of the second attachment part.
 6. The connector of claim 4, wherein the second portion is a fastening means and comprises a snap pin.
 7. The connector of claim 4, wherein the first portion comprises an elongate tail protruding therefrom.
 8. A connector for connecting inner and outer layers of an apparatus, the connector comprising: a first attachment part for attaching to one of the inner or outer layers; a second attachment part for attaching to the other of the inner or outer layers; and a resilient member connecting the first and second attachment parts; wherein: the resilient member is configured to be arranged between the inner and outer layers and to extend in a direction substantially parallel to a plane of the inner and outer layers, when the connector is attached to the inner and outer layers; and the resilient member is biased, when in a neutral state, in a direction perpendicular to a plane of the inner and outer layers, when the connector is attached to the inner and outer layers, such that when the first attachment part is attached to said one of the inner or outer layers, the second attachment part is pressed against said one of the inner or outer layers.
 9. The connector of claim 8, wherein the first attachment part comprises: a first flange portion, adjacent a gap, said gap for accommodating a portion of said one of the inner or outer layers, said first flange portions retaining said inner or outer layers within said gap, and wherein wherein the first flange portion is substantially dome-shaped.
 10. The connector of claim 8, wherein the first attachment part comprises: a first flange portion, adjacent a gap, said gap for accommodating a portion of said one of the inner or outer layer, said first flange portion retaining said inner or outer layers within said gap; separate first and second sections, the first section configured to connect directly to said one of the inner or outer layers, the second section configured to connect the rest of the connector to the first section, wherein: the first section of the first attachment part comprises: the first flange portion, located at a perimeter portion of the first section; a recessed portion, located at a central region of the first section, within the perimeter portion; a through hole through the recessed portion; and the second section of the first attachment part comprises: a further flanged portion configured to be located within the recessed portion of the first section, and a neck portion configured to pass through the through hole of the first section, the neck portion being connected to the rest of the connector.
 11. The connector of claim 8, wherein the second attachment part comprises: a first portion having a through hole therein; and a second portion passing through the through hole and configured to attach to said other of the inner or outer layers; wherein; the first portion of the second attachment part is configured such that the first portion can be threaded through a hole in said one of the inner or outer layers and the first attachment part is configured such that the first attachment part cannot be threaded through said hole.
 12. An apparatus comprising: inner and outer layers configured to move relative to each other; at least one connector according to claim 1 connecting the inner and outer layers.
 13. The apparatus of claim 12, wherein the inner and outer layers are configured to move relative to each other at a sliding interface.
 14. The apparatus of claim 12, wherein the apparatus is an item of protective headgear.
 15. The apparatus of claim 14, wherein the first attachment part is attached to the inner layer.
 16. The apparatus of claim 15, wherein the inner layer is an interface layer configured to interface with the head of a wearer.
 17. A method of assembling an apparatus according to claim 12, the method comprising: threading the second attachment part through a hole in said one of the inner or outer layers until the first attachment part is adjacent the hole; attaching the first attachment part to said one of the inner or outer layers, at the hole, via the first flange portion; and attaching the second attachment part to the other of the inner or outer layer.
 18. The connector of claim 4, wherein the first attachment part comprises: a first flange portion, adjacent a gap, said gap for accommodating a portion of said one of the inner or outer layers, said first flange portions retaining said inner or outer layers within said gap, and wherein wherein the first flange portion is substantially dome-shaped.
 19. The connector of claim 4, wherein the first attachment part comprises: a first flange portion, adjacent a gap, said gap for accommodating a portion of said one of the inner or outer layer, said first flange portion retaining said inner or outer layers within said gap; separate first and second sections, the first section configured to connect directly to said one of the inner or outer layers, the second section configured to connect the rest of the connector to the first section, wherein: the first section of the first attachment part comprises: the first flange portion, located at a perimeter portion of the first section; a recessed portion, located at a central region of the first section, within the perimeter portion; a through hole through the recessed portion; and the second section of the first attachment part comprises: a further flanged portion configured to be located within the recessed portion of the first section, and a neck portion configured to pass through the through hole of the first section, the neck portion being connected to the rest of the connector. 